Some known vehicles monitor the geographic locations of the vehicles as the vehicles move. For example, some rail vehicles travel according to schedules or plans that dictate where the rail vehicles move. As another example, some automobiles move (or are controlled to move) according to direction from global positioning systems (GPS) that dictate where the automobiles are to travel.
A vehicle may travel through intersections or points of divergence where a route or path that the vehicle is currently traveling along splits or divides into multiple different routes or paths. The schedules or plans of the vehicle may direct the vehicle to travel along a particular or designated route of the several routes or paths. Due to operator error, malfunctioning equipment (e.g., malfunctioning switches at a railway), and the like, however, the vehicle may take a different route or path and diverge away from the designated path or route.
Some known systems use the longitude and latitude data provided by GPS to determine if the vehicles are traveling on the correct or designated path or route. For example, these systems may obtain a longitude and latitude from a GPS receiver that represents the location of the vehicle at a point in time. The systems can then use this longitude and latitude in an attempt to determine where the vehicle is along a route. But, the resolution of GPS may be limited such that the systems may be unable to determine if the vehicle is on the correct path or route until the vehicle has traveled a significant distance along the route. For example, in rail yards, the different tracks may be spaced closer together than the resolution of the GPS can distinguish between, and this close spacing may be maintained (e.g., in the case of parallel or non-intersecting adjacent tracks) for a significant distance. Similarly, at switch points (e.g., intersections of several routes or tracks at a switch), the routes or tracks may be relatively close together in the vicinity of the switch point. As a result, the GPS may be unable to determine which route or track the vehicle is traveling along.